fs/xfs/xfs_attr_leaf.h

   1 /*
   2  * Copyright (c) 2000,2002-2003,2005 Silicon Graphics, Inc.
   3  * Copyright (c) 2013 Red Hat, Inc.
   4  * All Rights Reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it would be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write the Free Software Foundation,
  17  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  18  */
  19 #ifndef __XFS_ATTR_LEAF_H__
  20 #define __XFS_ATTR_LEAF_H__
  21
  22 /*
  23  * Attribute storage layout, internal structure, access macros, etc.
  24  *
  25  * Attribute lists are structured around Btrees where all the data
  26  * elements are in the leaf nodes.  Attribute names are hashed into an int,
  27  * then that int is used as the index into the Btree.  Since the hashval
  28  * of an attribute name may not be unique, we may have duplicate keys.  The
  29  * internal links in the Btree are logical block offsets into the file.
  30  */
  31
  32 struct attrlist;
  33 struct attrlist_cursor_kern;
  34 struct xfs_attr_list_context;
  35 struct xfs_da_args;
  36 struct xfs_da_state;
  37 struct xfs_da_state_blk;
  38 struct xfs_inode;
  39 struct xfs_trans;
  40
  41 /*========================================================================
  42  * Attribute structure when equal to XFS_LBSIZE(mp) bytes.
  43  *========================================================================*/
  44
  45 /*
  46  * This is the structure of the leaf nodes in the Btree.
  47  *
  48  * Struct leaf_entry's are packed from the top.  Name/values grow from the
  49  * bottom but are not packed.  The freemap contains run-length-encoded entries
  50  * for the free bytes after the leaf_entry's, but only the N largest such,
  51  * smaller runs are dropped.  When the freemap doesn't show enough space
  52  * for an allocation, we compact the name/value area and try again.  If we
  53  * still don't have enough space, then we have to split the block.  The
  54  * name/value structs (both local and remote versions) must be 32bit aligned.
  55  *
  56  * Since we have duplicate hash keys, for each key that matches, compare
  57  * the actual name string.  The root and intermediate node search always
  58  * takes the first-in-the-block key match found, so we should only have
  59  * to work "forw"ard.  If none matches, continue with the "forw"ard leaf
  60  * nodes until the hash key changes or the attribute name is found.
  61  *
  62  * We store the fact that an attribute is a ROOT/USER/SECURE attribute in
  63  * the leaf_entry.  The namespaces are independent only because we also look
  64  * at the namespace bit when we are looking for a matching attribute name.
  65  *
  66  * We also store an "incomplete" bit in the leaf_entry.  It shows that an
  67  * attribute is in the middle of being created and should not be shown to
  68  * the user if we crash during the time that the bit is set.  We clear the
  69  * bit when we have finished setting up the attribute.  We do this because
  70  * we cannot create some large attributes inside a single transaction, and we
  71  * need some indication that we weren't finished if we crash in the middle.
  72  */
  73 #define XFS_ATTR_LEAF_MAPSIZE   3       /* how many freespace slots */
  74
  75 typedef struct xfs_attr_leaf_map {      /* RLE map of free bytes */
  76         __be16  base;                     /* base of free region */
  77         __be16  size;                     /* length of free region */
  78 } xfs_attr_leaf_map_t;
  79
  80 typedef struct xfs_attr_leaf_hdr {      /* constant-structure header block */
  81         xfs_da_blkinfo_t info;          /* block type, links, etc. */
  82         __be16  count;                  /* count of active leaf_entry's */
  83         __be16  usedbytes;              /* num bytes of names/values stored */
  84         __be16  firstused;              /* first used byte in name area */
  85         __u8    holes;                  /* != 0 if blk needs compaction */
  86         __u8    pad1;
  87         xfs_attr_leaf_map_t freemap[XFS_ATTR_LEAF_MAPSIZE];
  88                                         /* N largest free regions */
  89 } xfs_attr_leaf_hdr_t;
  90
  91 typedef struct xfs_attr_leaf_entry {    /* sorted on key, not name */
  92         __be32  hashval;                /* hash value of name */
  93         __be16  nameidx;                /* index into buffer of name/value */
  94         __u8    flags;                  /* LOCAL/ROOT/SECURE/INCOMPLETE flag */
  95         __u8    pad2;                   /* unused pad byte */
  96 } xfs_attr_leaf_entry_t;
  97
  98 typedef struct xfs_attr_leaf_name_local {
  99         __be16  valuelen;               /* number of bytes in value */
 100         __u8    namelen;                /* length of name bytes */
 101         __u8    nameval[1];             /* name/value bytes */
 102 } xfs_attr_leaf_name_local_t;
 103
 104 typedef struct xfs_attr_leaf_name_remote {
 105         __be32  valueblk;               /* block number of value bytes */
 106         __be32  valuelen;               /* number of bytes in value */
 107         __u8    namelen;                /* length of name bytes */
 108         __u8    name[1];                /* name bytes */
 109 } xfs_attr_leaf_name_remote_t;
 110
 111 typedef struct xfs_attr_leafblock {
 112         xfs_attr_leaf_hdr_t     hdr;    /* constant-structure header block */
 113         xfs_attr_leaf_entry_t   entries[1];     /* sorted on key, not name */
 114         xfs_attr_leaf_name_local_t namelist;    /* grows from bottom of buf */
 115         xfs_attr_leaf_name_remote_t valuelist;  /* grows from bottom of buf */
 116 } xfs_attr_leafblock_t;
 117
 118 /*
 119  * CRC enabled leaf structures. Called "version 3" structures to match the
 120  * version number of the directory and dablk structures for this feature, and
 121  * attr2 is already taken by the variable inode attribute fork size feature.
 122  */
 123 struct xfs_attr3_leaf_hdr {
 124         struct xfs_da3_blkinfo  info;
 125         __be16                  count;
 126         __be16                  usedbytes;
 127         __be16                  firstused;
 128         __u8                    holes;
 129         __u8                    pad1;
 130         struct xfs_attr_leaf_map freemap[XFS_ATTR_LEAF_MAPSIZE];
 131         __be32                  pad2;           /* 64 bit alignment */
 132 };
 133
 134 #define XFS_ATTR3_LEAF_CRC_OFF  (offsetof(struct xfs_attr3_leaf_hdr, info.crc))
 135
 136 struct xfs_attr3_leafblock {
 137         struct xfs_attr3_leaf_hdr       hdr;
 138         struct xfs_attr_leaf_entry      entries[1];
 139
 140         /*
 141          * The rest of the block contains the following structures after the
 142          * leaf entries, growing from the bottom up. The variables are never
 143          * referenced, the locations accessed purely from helper functions.
 144          *
 145          * struct xfs_attr_leaf_name_local
 146          * struct xfs_attr_leaf_name_remote
 147          */
 148 };
 149
 150 /*
 151  * incore, neutral version of the attribute leaf header
 152  */
 153 struct xfs_attr3_icleaf_hdr {
 154         __uint32_t      forw;
 155         __uint32_t      back;
 156         __uint16_t      magic;
 157         __uint16_t      count;
 158         __uint16_t      usedbytes;
 159         __uint16_t      firstused;
 160         __u8            holes;
 161         struct {
 162                 __uint16_t      base;
 163                 __uint16_t      size;
 164         } freemap[XFS_ATTR_LEAF_MAPSIZE];
 165 };
 166
 167 /*
 168  * Flags used in the leaf_entry[i].flags field.
 169  * NOTE: the INCOMPLETE bit must not collide with the flags bits specified
 170  * on the system call, they are "or"ed together for various operations.
 171  */
 172 #define XFS_ATTR_LOCAL_BIT      0       /* attr is stored locally */
 173 #define XFS_ATTR_ROOT_BIT       1       /* limit access to trusted attrs */
 174 #define XFS_ATTR_SECURE_BIT     2       /* limit access to secure attrs */
 175 #define XFS_ATTR_INCOMPLETE_BIT 7       /* attr in middle of create/delete */
 176 #define XFS_ATTR_LOCAL          (1 << XFS_ATTR_LOCAL_BIT)
 177 #define XFS_ATTR_ROOT           (1 << XFS_ATTR_ROOT_BIT)
 178 #define XFS_ATTR_SECURE         (1 << XFS_ATTR_SECURE_BIT)
 179 #define XFS_ATTR_INCOMPLETE     (1 << XFS_ATTR_INCOMPLETE_BIT)
 180
 181 /*
 182  * Conversion macros for converting namespace bits from argument flags
 183  * to ondisk flags.
 184  */
 185 #define XFS_ATTR_NSP_ARGS_MASK          (ATTR_ROOT | ATTR_SECURE)
 186 #define XFS_ATTR_NSP_ONDISK_MASK        (XFS_ATTR_ROOT | XFS_ATTR_SECURE)
 187 #define XFS_ATTR_NSP_ONDISK(flags)      ((flags) & XFS_ATTR_NSP_ONDISK_MASK)
 188 #define XFS_ATTR_NSP_ARGS(flags)        ((flags) & XFS_ATTR_NSP_ARGS_MASK)
 189 #define XFS_ATTR_NSP_ARGS_TO_ONDISK(x)  (((x) & ATTR_ROOT ? XFS_ATTR_ROOT : 0) |\
 190                                          ((x) & ATTR_SECURE ? XFS_ATTR_SECURE : 0))
 191 #define XFS_ATTR_NSP_ONDISK_TO_ARGS(x)  (((x) & XFS_ATTR_ROOT ? ATTR_ROOT : 0) |\
 192                                          ((x) & XFS_ATTR_SECURE ? ATTR_SECURE : 0))
 193
 194 /*
 195  * Alignment for namelist and valuelist entries (since they are mixed
 196  * there can be only one alignment value)
 197  */
 198 #define XFS_ATTR_LEAF_NAME_ALIGN        ((uint)sizeof(xfs_dablk_t))
 199
 200 static inline int
 201 xfs_attr3_leaf_hdr_size(struct xfs_attr_leafblock *leafp)
 202 {
 203         if (leafp->hdr.info.magic == cpu_to_be16(XFS_ATTR3_LEAF_MAGIC))
 204                 return sizeof(struct xfs_attr3_leaf_hdr);
 205         return sizeof(struct xfs_attr_leaf_hdr);
 206 }
 207
 208 static inline struct xfs_attr_leaf_entry *
 209 xfs_attr3_leaf_entryp(xfs_attr_leafblock_t *leafp)
 210 {
 211         if (leafp->hdr.info.magic == cpu_to_be16(XFS_ATTR3_LEAF_MAGIC))
 212                 return &((struct xfs_attr3_leafblock *)leafp)->entries[0];
 213         return &leafp->entries[0];
 214 }
 215
 216 /*
 217  * Cast typed pointers for "local" and "remote" name/value structs.
 218  */
 219 static inline char *
 220 xfs_attr3_leaf_name(xfs_attr_leafblock_t *leafp, int idx)
 221 {
 222         struct xfs_attr_leaf_entry *entries = xfs_attr3_leaf_entryp(leafp);
 223
 224         return &((char *)leafp)[be16_to_cpu(entries[idx].nameidx)];
 225 }
 226
 227 static inline xfs_attr_leaf_name_remote_t *
 228 xfs_attr3_leaf_name_remote(xfs_attr_leafblock_t *leafp, int idx)
 229 {
 230         return (xfs_attr_leaf_name_remote_t *)xfs_attr3_leaf_name(leafp, idx);
 231 }
 232
 233 static inline xfs_attr_leaf_name_local_t *
 234 xfs_attr3_leaf_name_local(xfs_attr_leafblock_t *leafp, int idx)
 235 {
 236         return (xfs_attr_leaf_name_local_t *)xfs_attr3_leaf_name(leafp, idx);
 237 }
 238
 239 /*
 240  * Calculate total bytes used (including trailing pad for alignment) for
 241  * a "local" name/value structure, a "remote" name/value structure, and
 242  * a pointer which might be either.
 243  */
 244 static inline int xfs_attr_leaf_entsize_remote(int nlen)
 245 {
 246         return ((uint)sizeof(xfs_attr_leaf_name_remote_t) - 1 + (nlen) + \
 247                 XFS_ATTR_LEAF_NAME_ALIGN - 1) & ~(XFS_ATTR_LEAF_NAME_ALIGN - 1);
 248 }
 249
 250 static inline int xfs_attr_leaf_entsize_local(int nlen, int vlen)
 251 {
 252         return ((uint)sizeof(xfs_attr_leaf_name_local_t) - 1 + (nlen) + (vlen) +
 253                 XFS_ATTR_LEAF_NAME_ALIGN - 1) & ~(XFS_ATTR_LEAF_NAME_ALIGN - 1);
 254 }
 255
 256 static inline int xfs_attr_leaf_entsize_local_max(int bsize)
 257 {
 258         return (((bsize) >> 1) + ((bsize) >> 2));
 259 }
 260
 261 /*
 262  * Used to keep a list of "remote value" extents when unlinking an inode.
 263  */
 264 typedef struct xfs_attr_inactive_list {
 265         xfs_dablk_t     valueblk;       /* block number of value bytes */
 266         int             valuelen;       /* number of bytes in value */
 267 } xfs_attr_inactive_list_t;
 268
 269
 270 /*========================================================================
 271  * Function prototypes for the kernel.
 272  *========================================================================*/
 273
 274 /*
 275  * Internal routines when attribute fork size < XFS_LITINO(mp).
 276  */
 277 void    xfs_attr_shortform_create(struct xfs_da_args *args);
 278 void    xfs_attr_shortform_add(struct xfs_da_args *args, int forkoff);
 279 int     xfs_attr_shortform_lookup(struct xfs_da_args *args);
 280 int     xfs_attr_shortform_getvalue(struct xfs_da_args *args);
 281 int     xfs_attr_shortform_to_leaf(struct xfs_da_args *args);
 282 int     xfs_attr_shortform_remove(struct xfs_da_args *args);
 283 int     xfs_attr_shortform_list(struct xfs_attr_list_context *context);
 284 int     xfs_attr_shortform_allfit(struct xfs_buf *bp, struct xfs_inode *dp);
 285 int     xfs_attr_shortform_bytesfit(xfs_inode_t *dp, int bytes);
 286
 287
 288 /*
 289  * Internal routines when attribute fork size == XFS_LBSIZE(mp).
 290  */
 291 int     xfs_attr3_leaf_to_node(struct xfs_da_args *args);
 292 int     xfs_attr3_leaf_to_shortform(struct xfs_buf *bp,
 293                                    struct xfs_da_args *args, int forkoff);
 294 int     xfs_attr3_leaf_clearflag(struct xfs_da_args *args);
 295 int     xfs_attr3_leaf_setflag(struct xfs_da_args *args);
 296 int     xfs_attr3_leaf_flipflags(struct xfs_da_args *args);
 297
 298 /*
 299  * Routines used for growing the Btree.
 300  */
 301 int     xfs_attr3_leaf_split(struct xfs_da_state *state,
 302                                    struct xfs_da_state_blk *oldblk,
 303                                    struct xfs_da_state_blk *newblk);
 304 int     xfs_attr3_leaf_lookup_int(struct xfs_buf *leaf,
 305                                         struct xfs_da_args *args);
 306 int     xfs_attr3_leaf_getvalue(struct xfs_buf *bp, struct xfs_da_args *args);
 307 int     xfs_attr3_leaf_add(struct xfs_buf *leaf_buffer,
 308                                  struct xfs_da_args *args);
 309 int     xfs_attr3_leaf_remove(struct xfs_buf *leaf_buffer,
 310                                     struct xfs_da_args *args);
 311 int     xfs_attr3_leaf_list_int(struct xfs_buf *bp,
 312                                       struct xfs_attr_list_context *context);
 313
 314 /*
 315  * Routines used for shrinking the Btree.
 316  */
 317 int     xfs_attr3_leaf_toosmall(struct xfs_da_state *state, int *retval);
 318 void    xfs_attr3_leaf_unbalance(struct xfs_da_state *state,
 319                                        struct xfs_da_state_blk *drop_blk,
 320                                        struct xfs_da_state_blk *save_blk);
 321 int     xfs_attr3_root_inactive(struct xfs_trans **trans, struct xfs_inode *dp);
 322
 323 /*
 324  * Utility routines.
 325  */
 326 xfs_dahash_t    xfs_attr_leaf_lasthash(struct xfs_buf *bp, int *count);
 327 int     xfs_attr_leaf_order(struct xfs_buf *leaf1_bp,
 328                                    struct xfs_buf *leaf2_bp);
 329 int     xfs_attr_leaf_newentsize(int namelen, int valuelen, int blocksize,
 330                                         int *local);
 331 int     xfs_attr3_leaf_read(struct xfs_trans *tp, struct xfs_inode *dp,
 332                         xfs_dablk_t bno, xfs_daddr_t mappedbno,
 333                         struct xfs_buf **bpp);
 334 void    xfs_attr3_leaf_hdr_from_disk(struct xfs_attr3_icleaf_hdr *to,
 335                                      struct xfs_attr_leafblock *from);
 336 void    xfs_attr3_leaf_hdr_to_disk(struct xfs_attr_leafblock *to,
 337                                    struct xfs_attr3_icleaf_hdr *from);
 338
 339 extern const struct xfs_buf_ops xfs_attr3_leaf_buf_ops;
 340
 341 #endif  /* __XFS_ATTR_LEAF_H__ */